This invention relates to improvements in rotary engines and in particular, relates to mechanisms for adjusting the compression chamber volume of a rotary engine, such that the effective displacement is varied, and relates to systems for delivering fuel to effect complete, fuel efficient combustion under varied operating conditions.
Rotary engines, particularly the Wankel-type engine which has found use in automotive applications, suffer from several recognized drawbacks that limit their performance and efficiency. These historic problems have penalized the general adoption of rotary engines, in spite of the fundamental advantage of a rotary piston for production of power to a rotational output shaft.
Among some of the recognized problems are:
the sealing system of the linear, one-blade, apex seal which is subjected to the full pressure differential between the two adjacent chambers on each side of the seal;
the design limitations on the maximum peripheral speed of conventional apex seals along the internal chamber wall of the housing;
the low rate of ignition and combustion of the fuel air mixture in the elongated, "bath-tub" shaped, combustion chamber that is continuously modified in volume and shape during compression and combustion in a manner that impedes effective combustion;
poor specific fuel consumption, with unusually high specific fuel consumption at part loads similar to gas turbines because of a fixed cycle configuration;
limited capability for supercharging spark ignited rotary engines that are provided with a carbureted or injected fuel intake because of preignition detonation; and
limited improvement in specific fuel consumption and supercharging levels rotary engines designs having staged pilot and main injection fueling systems enabling multi-fuel capability.
Common to the problems in the state of the art technologies attempting to improve the performance of rotary engines is the reliance on designs which retain the constant displacement of the intake/compression side of the engine. This design feature presents an obstacle to attempts to raise the power density by employing high levels of supercharging since the fixed chamber configuration requires the use of a "waste gate" for turbocharged rotary engines and results in overfueling to maintain combustion at less than optimum loads.
It would be desirable to devise a system that enables the power density of a rotary engine to be improved by a very high supercharging level and to maintain a flat specific fuel consumption by constant combustion pressure and constant compression pressure at high and low load, and at high and low rotation.
The improved rotary engine design of this invention incorporates novel features to solve the problems that exist in current, fixed geometry, rotary engines, particularly standard chamber configurations of Wankel-type epitrochoidal engines.